1.\" Copyright (c) 1980, 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the Institute of Electrical and Electronics Engineers, Inc. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 4. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)date.1 8.3 (Berkeley) 4/28/95 32.\" $FreeBSD$ 33.\" 34.Dd August 9, 2004 35.Dt DATE 1 36.Os 37.Sh NAME 38.Nm date 39.Nd display or set date and time 40.Sh SYNOPSIS 41.Nm 42.Op Fl ju 43.Op Fl r Ar seconds 44.Oo 45.Fl v 46.Sm off 47.Op Cm + | - 48.Ar val Op Ar ymwdHMS 49.Sm on 50.Oc 51.Ar ... 52.Op Cm + Ns Ar output_fmt 53.Nm 54.Op Fl jnu 55.Sm off 56.Op Oo Oo Oo Oo Ar cc Oc Ar yy Oc Ar mm Oc Ar dd Oc Ar HH 57.Ar MM Op Ar .ss 58.Sm on 59.Nm 60.Op Fl jnu 61.Fl f Ar input_fmt new_date 62.Op Cm + Ns Ar output_fmt 63.Nm 64.Op Fl d Ar dst 65.Op Fl t Ar minutes_west 66.Sh DESCRIPTION 67When invoked without arguments, the 68.Nm 69utility displays the current date and time. 70Otherwise, depending on the options specified, 71.Nm 72will set the date and time or print it in a user-defined way. 73.Pp 74The 75.Nm 76utility displays the date and time read from the kernel clock. 77When used to set the date and time, 78both the kernel clock and the hardware clock are updated. 79.Pp 80Only the superuser may set the date, 81and if the system securelevel (see 82.Xr securelevel 8 ) 83is greater than 1, 84the time may not be changed by more than 1 second. 85.Pp 86The options are as follows: 87.Bl -tag -width Ds 88.It Fl d Ar dst 89Set the kernel's value for daylight saving time. 90If 91.Ar dst 92is non-zero, future calls 93to 94.Xr gettimeofday 2 95will return a non-zero for 96.Fa tz_dsttime . 97.It Fl f 98Use 99.Ar input_fmt 100as the format string to parse the 101.Ar new_date 102provided rather than using the default 103.Sm off 104.Oo Oo Oo Oo Oo 105.Ar cc Oc 106.Ar yy Oc 107.Ar mm Oc 108.Ar dd Oc 109.Ar HH 110.Oc Ar MM Op Ar .ss 111.Sm on 112format. 113Parsing is done using 114.Xr strptime 3 . 115.It Fl j 116Do not try to set the date. 117This allows you to use the 118.Fl f 119flag in addition to the 120.Cm + 121option to convert one date format to another. 122.It Fl n 123By default, if the 124.Xr timed 8 125daemon is running, 126.Nm 127sets the time on all of the machines in the local group. 128The 129.Fl n 130option suppresses this behavior and causes the time to be set only on the 131current machine. 132.It Fl r Ar seconds 133Print the date and time represented by 134.Ar seconds , 135where 136.Ar seconds 137is the number of seconds since the Epoch 138(00:00:00 UTC, January 1, 1970; 139see 140.Xr time 3 ) , 141and can be specified in decimal, octal, or hex. 142.It Fl t Ar minutes_west 143Set the system's value for minutes west of 144.Tn GMT . 145.Ar minutes_west 146specifies the number of minutes returned in 147.Fa tz_minuteswest 148by future calls to 149.Xr gettimeofday 2 . 150.It Fl u 151Display or set the date in 152.Tn UTC 153(Coordinated Universal) time. 154.It Fl v 155Adjust (i.e., take the current date and display the result of the 156adjustment; not actually set the date) the second, minute, hour, month 157day, week day, month or year according to 158.Ar val . 159If 160.Ar val 161is preceded with a plus or minus sign, 162the date is adjusted forwards or backwards according to the remaining string, 163otherwise the relevant part of the date is set. 164The date can be adjusted as many times as required using these flags. 165Flags are processed in the order given. 166.Pp 167When setting values 168(rather than adjusting them), 169seconds are in the range 0-59, minutes are in the range 0-59, hours are 170in the range 0-23, month days are in the range 1-31, week days are in the 171range 0-6 (Sun-Sat), 172months are in the range 1-12 (Jan-Dec) 173and years are in the range 80-38 or 1980-2038. 174.Pp 175If 176.Ar val 177is numeric, one of either 178.Ar y , 179.Ar m , 180.Ar w , 181.Ar d , 182.Ar H , 183.Ar M 184or 185.Ar S 186must be used to specify which part of the date is to be adjusted. 187.Pp 188The week day or month may be specified using a name rather than a 189number. 190If a name is used with the plus 191(or minus) 192sign, the date will be put forwards 193(or backwards) 194to the next 195(previous) 196date that matches the given week day or month. 197This will not adjust the date, 198if the given week day or month is the same as the current one. 199.Pp 200When a date is adjusted to a specific value or in units greater than hours, 201daylight savings time considerations are ignored. 202Adjustments in units of hours or less honor daylight saving time. 203So, assuming the current date is March 26, 0:30 and that the DST adjustment 204means that the clock goes forward at 01:00 to 02:00, using 205.Fl v No +1H 206will adjust the date to March 26, 2:30. 207Likewise, if the date is October 29, 0:30 and the DST adjustment means that 208the clock goes back at 02:00 to 01:00, using 209.Fl v No +3H 210will be necessary to reach October 29, 2:30. 211.Pp 212When the date is adjusted to a specific value that doesn't actually exist 213(for example March 26, 1:30 BST 2000 in the Europe/London timezone), 214the date will be silently adjusted forwards in units of one hour until it 215reaches a valid time. 216When the date is adjusted to a specific value that occurs twice 217(for example October 29, 1:30 2000), 218the resulting timezone will be set so that the date matches the earlier of 219the two times. 220.Pp 221Adjusting the date by months is inherently ambiguous because 222a month is a unit of variable length depending on the current date. 223This kind of date adjustment is applied in the most intuitive way. 224First of all, 225.Nm 226tries to preserve the day of the month. 227If it is impossible because the target month is shorter than the present one, 228the last day of the target month will be the result. 229For example, using 230.Fl v No +1m 231on May 31 will adjust the date to June 30, while using the same option 232on January 30 will result in the date adjusted to the last day of February. 233This approach is also believed to make the most sense for shell scripting. 234Nevertheless, be aware that going forth and back by the same number of 235months may take you to a different date. 236.Pp 237Refer to the examples below for further details. 238.El 239.Pp 240An operand with a leading plus 241.Pq Sq + 242sign signals a user-defined format string 243which specifies the format in which to display the date and time. 244The format string may contain any of the conversion specifications 245described in the 246.Xr strftime 3 247manual page, as well as any arbitrary text. 248A newline 249.Pq Ql \en 250character is always output after the characters specified by 251the format string. 252The format string for the default display is 253.Dq +%+ . 254.Pp 255If an operand does not have a leading plus sign, it is interpreted as 256a value for setting the system's notion of the current date and time. 257The canonical representation for setting the date and time is: 258.Pp 259.Bl -tag -width Ds -compact -offset indent 260.It Ar cc 261Century 262(either 19 or 20) 263prepended to the abbreviated year. 264.It Ar yy 265Year in abbreviated form 266(e.g., 89 for 1989, 06 for 2006). 267.It Ar mm 268Numeric month, a number from 1 to 12. 269.It Ar dd 270Day, a number from 1 to 31. 271.It Ar HH 272Hour, a number from 0 to 23. 273.It Ar MM 274Minutes, a number from 0 to 59. 275.It Ar ss 276Seconds, a number from 0 to 61 277(59 plus a maximum of two leap seconds). 278.El 279.Pp 280Everything but the minutes is optional. 281.Pp 282Time changes for Daylight Saving Time, standard time, leap seconds, 283and leap years are handled automatically. 284.Sh EXAMPLES 285The command: 286.Pp 287.Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S""" 288.Pp 289will display: 290.Bd -literal -offset indent 291DATE: 1987-11-21 292TIME: 13:36:16 293.Ed 294.Pp 295In the Europe/London timezone, the command: 296.Pp 297.Dl "date -v1m -v+1y" 298.Pp 299will display: 300.Pp 301.Dl "Sun Jan 4 04:15:24 GMT 1998" 302.Pp 303where it is currently 304.Li "Mon Aug 4 04:15:24 BST 1997" . 305.Pp 306The command: 307.Pp 308.Dl "date -v1d -v3m -v0y -v-1d" 309.Pp 310will display the last day of February in the year 2000: 311.Pp 312.Dl "Tue Feb 29 03:18:00 GMT 2000" 313.Pp 314So will do the command: 315.Pp 316.Dl "date -v30d -v3m -v0y -v-1m" 317.Pp 318because there is no such date as the 30th of February. 319.Pp 320The command: 321.Pp 322.Dl "date -v1d -v+1m -v-1d -v-fri" 323.Pp 324will display the last Friday of the month: 325.Pp 326.Dl "Fri Aug 29 04:31:11 BST 1997" 327.Pp 328where it is currently 329.Li "Mon Aug 4 04:31:11 BST 1997" . 330.Pp 331The command: 332.Pp 333.Dl "date 8506131627" 334.Pp 335sets the date to 336.Dq Li "June 13, 1985, 4:27 PM" . 337.Pp 338.Dl "date ""+%Y%m%d%H%M.%S""" 339.Pp 340may be used on one machine to print out the date 341suitable for setting on another. 342.Qq ( Li "+%m%d%H%M%Y.%S" 343for use on 344.Tn Linux . ) 345.Pp 346The command: 347.Pp 348.Dl "date 1432" 349.Pp 350sets the time to 351.Li "2:32 PM" , 352without modifying the date. 353.Pp 354Finally the command: 355.Pp 356.Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`date`"" ""+%s""" 357.Pp 358can be used to parse the ouput from 359.Nm 360and express it in epoch time. 361.Sh ENVIRONMENT 362The following environment variables affect the execution of 363.Nm : 364.Bl -tag -width Ds 365.It Ev TZ 366The timezone to use when displaying dates. 367The normal format is a pathname relative to 368.Pa /usr/share/zoneinfo . 369For example, the command 370.Dq TZ=America/Los_Angeles date 371displays the current time in California. 372See 373.Xr environ 7 374for more information. 375.El 376.Sh FILES 377.Bl -tag -width /var/log/messages -compact 378.It Pa /var/log/wtmp 379record of date resets and time changes 380.It Pa /var/log/messages 381record of the user setting the time 382.El 383.Sh SEE ALSO 384.Xr gettimeofday 2 , 385.Xr strftime 3 , 386.Xr strptime 3 , 387.Xr utmp 5 , 388.Xr timed 8 389.Rs 390.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" 391.%A R. Gusella 392.%A S. Zatti 393.Re 394.Sh DIAGNOSTICS 395The 396.Nm 397utility exits 0 on success, 1 if unable to set the date, and 2 398if able to set the local date, but unable to set it globally. 399.Pp 400Occasionally, when 401.Xr timed 8 402synchronizes the time on many hosts, the setting of a new time value may 403require more than a few seconds. 404On these occasions, 405.Nm 406prints: 407.Ql Network time being set . 408The message 409.Ql Communication error with timed 410occurs when the communication 411between 412.Nm 413and 414.Xr timed 8 415fails. 416.Sh STANDARDS 417The 418.Nm 419utility is expected to be compatible with 420.St -p1003.2 . 421.Sh HISTORY 422A 423.Nm 424command appeared in 425.At v1 . 426